In a conventional green tire forming technique, for example, as shown in FIG. 12, a belt-tread assembly is formed by a belt former 101 on one side; a green carcass is formed by a green-tire former 102 on the other side; beads are held by bead setting mechanisms 103A, 103B respectively; the beads are moved to be set at a predetermined positions on the tire former 102 by air cylinders 104A, 104B; the beads are fixed with the green carcass by extending the diameters of bead lock mechanisms integrated in a first and a second shoulder formers 106A, 106B; the belt-tread assembly formed by the belt former 101 is positioned on the periphery of the green carcass by a transferring mechanism 105; the green carcass is toroidally shaped by feeding shaping air inside the green carcass while moving both shoulder formers 106A, 106B inwardly to each other by, a driving mechanism (not shown); the belt-tread assembly is attached to the green carcass; both edges of the carcass ply are turned up around the beads by expanding ply turn-up bladders provided to the first and the second shoulder formers 106A, 106B; the ply turn-up bladders are further pressed from both outsides by expanding pressing bladders (for example, Japanese Examined Patent Publication No. 70548/1984) provided outside of the ply turn-up bladders the turned-up portion and the side walls of the carcass ply are firmly fixed to the body of the carcass to complete a green tire.
A conventional apparatus employed in this kind of green tire forming technique is generally much complicated in mechanism as mentioned above. In the apparatus, for example, the bead setting mechanisms (the bead setters 103A, 103B) for setting beads at predetermined positions on a green carcass arranged on a green tire former, and pressing mechanisms (pressing bladders) for pressing ply turn-up bladders from sides thereof are independently and separately provided.
Also, in the conventional tire forming apparatus, in order to hold and release belt-tread assembly the transferring mechanism utilizes a plurality of segments constituting an inner surface corresponding to the outer surface of the assembly, and a bladder or an air cylinder operated with air pressure for increasing or decreasing the inner diameter of an annular portion constituted by the segments, namely for extension or reduction of the segment. Accordingly, in holding the belt-tread assembly to position it at the periphery of the green carcass and combining the assembly with the green carcass which is shaped toroidaly, the air is pressurized to retreat the segments when the belt-tread assembly is pushed outward by expansion force of green carcass generated by inner pressure for shaping and the resulting pressurizing force is applied to the bladder or the air cylinder, the drive of the segments, via the segments. As a result, the outer diameter of the belt and tread are expanded undesirably, so that there arises a problem that a defective tire is produced. Further, when the belt-tread assembly is combined with the green carcass, as illustrated inside a dotted circle C in FIG. 11, both edges of the assembly are not firmly adhered to the green carcass, so that it is necessary to press the edges by a stitcher afterward. As a result, there also arises a problem that, when pressurizing, the breaker edge is deformed, or cords are snaked or separated whereby the uniformity of a tire is badly influenced.
Further, in order to take out a produced green tire from the tire former, an exclusive take-out mechanism is provided separately, or the segments of the transferring mechanism are utilized. However, there are such drawbacks that the apparatus becomes complicated when the take-out mechanism is separately provided, and it takes much time for taking out the produced green tire from the transferring mechanism when the segment are used.
The present invention is made to solve the above-mentioned drawbacks of the conventional art. It is an object of the present invention is to provide a green tire forming apparatus and a green tire forming method; wherein constructions of the bead setter and the ply turn-up bladder mechanism are simplified sharply, each segment of belt transferring mechanism is maintained at the predetermined position against the expansion force of the carcass when the belt-tread assembly are combined with the green carcass whereby the undesirable expansion of the outside diameters of belt and tread are prevented and production of defective tire is reduced, and it is easy to take out the green tire whereby operation efficiency is improved.
That is, it is an object of a first aspect of the present invention to provide a green tire forming apparatus and a method for forming the green tire; the main aim or which is to simplify the construction thereof by employing a construction wherein a function for pressing the ply turn-up bladder is added to the bead setting mechanism and the bead setting mechanism is moved to the tire former side by the transferring mechanism.
Also, it is an object of a second aspect of the present invention to provide a green tire forming apparatus of which main aim is to prevent the outside diameters of belt and tread from undesirably expanding in toroidal shaping of green carcass by employing a hydraulic mechanism as a driving means for expansion and reduction of each segment of the transferring mechanism.
Further, it is an object of a third aspect of the present invention to provide a green tire forming apparatus of which main aim is to improve the green tire take-out mechanism by integratedly combining the green tire take-out mechanism into the transferring mechanism.